Comparative Study of the Ability of Three Martian Simulants to Support
Bacterial Growth
Abstract
One key question about Mars is whether life has been or still is present
on or beneath its surface. For life to flourish, it requires a habitable
environment with the appropriate physical and chemical regolith
parameters. To better understand the parameters that constitute a
habitable environment, leachates of three martian simulants (JSC Mars-1,
MMS-1 fine, and MGS-1) were analyzed for their soluble ionic
composition, pH, and conductivity in order to determine the presence of
any beneficial or toxic elements and their effects on the two bacteria
E. coli and Eucapsis. E.coli was cultured in minimal media where acetic
acid was the only organic source, and tested its requirements for a
carbon source (acetic acid), nitrogen source
((NH4)2SO4) as well as
trace elements (Ca, Mn, Zn, Cu, Fe, Co, Mo). In minimal culture media
with all nutrients available for healthy growth, E. coli showed
substantial growth. In the case of a carbon-only source or nitrogen-only
source in MMS-1 soil leachate, E. coli showed limited growth compared to
that observed in the full minimal culture media. Assessing Eucapsis
growth, among the three leachates tested MMS-1 displayed the best
growth. Additionally, we observed that MMS-1+Allen’s minimal and full
Allen’s medium groups displayed similar growth curves, indicating that
MMS-1 can provide all the trace elements needed for Eucapsis growth.
Among all the leachates, MMS-1 showed the most promising results. MMS-1
+ Allen’s medium provided the highest Eucapsis growth. MGS-1 + Allen’s
minimal media also showed significantly higher growth than MGS-1 alone.
However, JSC and JSC + Allen’s minimal did not show any significant
difference regarding Eucapsis growth. The results indicated that
Eucapsis grew best in both MMS-1 F leachate only and MMS-1 F leachate
with Allen’s minimal medium.